Cauliflower Gratin

Preheat oven to 375 F. In a large pot of boiling salted water, cook the cauliflower until tender but still firm, about 5-6 minutes. Drain and set aside.
Add 2 tablespoons of the butter to a medium saucepan set over low heat. Once it melts, add the flour and cook for 2 minutes, stirring constantly with a wooden spoon. Slowly add the hot milk to the pan (to avoid dirtying another pot, I microwaved the milk in a 4-cup measuring cup for 2 minutes). Bring the mixture to a boil, whisking often. Once the milk begins to boil, whisk constantly for about 1 more minute, or until thickened. Remove the pot from the heat and add 1 teaspoon of coarse salt, the pepper, nutmeg, 1/2 cup of the Gruyere, and the Parmesan. Whisk together until you have a smooth sauce.
Pour about 1/3 of the sauce over the bottom of a 9-inch round pie plate (an 8x11 baking dish would work too). Spread the drained cauliflower evenly in the pan then pour the remaining sauce over the top. In a small bowl combine the bread crumbs and the remaining 1/4-cup of Gruyere. Sprinkle the mixture evenly over the top of the gratin. Melt the remaining 2 tablespoons of butter and drizzle them over the gratin. Finally, sprinkle the gratin with salt and pepper. Bake for 25-30 minutes, or until the top is browned.